I make oat bran porridge in a 4 cup measure which has had it markings worn off. 1/3 cup oat bran plus 1 cup water makes 1 serving. Micro on high for 1 minute, stir, micro for another minute, stir, micro for 15 seconds stir, micro for 10 sec. Sounds fussy but at 2 minutes 25 seconds it is pretty fast. This method was originally for quick oatmeal (not instant).
The oatmeal boils up fast and if you try to do the whole time at one go you will have oatmeal all over your turntable.
L